Empetrum nigrum

Black crowberry (Empetrum nigrum)
Scientific name	Empetrum nigrum
Common names	Black crowberry; crowberry
Genus	Empetrum
Family	Ericaceae
Order	Ericales
Native range	Subarctic to subalpine Northern Hemisphere; circumpolar in Alaska, northern Canada, Greenland, New England, the Great Lakes and Pacific-coast states, and across Europe
Habit	Low creeping evergreen mat-former, generally 6–25 cm tall, with trailing stems that root wherever they touch the ground
Fruit	Black, sometimes slightly waxy drupe 4–10 mm with six to nine nutlets; small, mealy and mild raw, cooked into jellies, pies, preserves and drinks
Propagation	Leafy stem cuttings root readily in peat; seed needs cold stratification and germinates slowly

Empetrum nigrum — the black crowberry, also called crowberry — is the accepted name of a low, creeping, evergreen shrub in the heather family Ericaceae.^[1][2] The GBIF backbone accepts the species with confidence 99 (usageKey 8925249), and Plants of the World Online records a native range across the subarctic to subalpine Northern Hemisphere.^[1][2] Synoecious tetraploid plants long treated as Empetrum hermaphroditum are now subsumed within E. nigrum in current floras; the older name survives mainly as a synonym for that tetraploid form.^[3][4]

The shrub forms dense, creeping mats generally about 15 cm (6 in) high, with clumps to about 25 cm (10 in) tall in some accounts, and trailing stems 50–100 cm long that root adventitiously where they contact the ground.^[3][5] Black drupes ripen in late summer and into fall, persist on the plant through winter — often under snow — and are gathered for jellies, pies, preserves and drinks; raw berries are small and mealy, and many accounts describe them as bland or better after frost.^[3][6]

Description

The plant is a low evergreen subshrub with slender, densely leafy branches that lie along the ground and root at the nodes, building mats over time; the leaves are linear-elliptic, with the lower surface grooved.^[3][7] Flowers are small and inconspicuous — pink-purplish, mostly solitary in the leaf axils of the previous season's growth — with sepals that are greenish pink at first and become reddish purple.^[5][4] Flower sexuality varies within the species: plants may be dioecious (male and female flowers on separate plants), synoecious with bisexual flowers, or polygamous.^[4][3] Diploid plants (2n = 26) are generally dioecious, while synoecious tetraploids (2n = 52) carry perfect flowers; chromosome counts of 2n = 39 (triploid) are also recorded.^[4] In North America the black-fruited plants of the genus are treated as E. nigrum in the broad sense, with the synoecious tetraploids formerly called E. hermaphroditum included.^[4]

The fruit is a black, opaque drupe 4–10 mm across — 5–10 mm in the Flora of North America treatment — sometimes with a thin white waxy coating, containing six to nine small nutlets and light-brown seeds 1.5–3 mm long.^[3][5][4][7]

Cultivation

In the wild the species spans a wide habitat range — sphagnum bogs, muskegs, open tundra, rockfields, conifer forests, coastal bluffs and alpine meadows — from sea level to roughly 2,500 m, so local performance depends strongly on matching the soil rather than the temperature envelope.^[7][5] Its native rhythm is a cold-climate one: growth and flowering track snowmelt, and the fruit crop is carried through winter on the plant.

Soil and water

Black crowberry is a calcifuge plant, easily grown in lime-free soil and preferring moist, sandy or peaty ground with some shade.^[6] Site records give a broad pH tolerance of roughly 2.5–7.7, and the UW propagation protocol lists a growth pH range of about 4.3–7.8; alkaline ground is the hard limit — a 2025 container study notes that E. nigrum cannot survive pH 8.0 and above because its ericoid mycorrhizal fungi die in alkaline conditions.^[3][7][8] The plants tolerate a wide soil-moisture range but not prolonged waterlogging; standing wet, anaerobic ground is consistently listed as an intolerance, while seasonal surface moisture is normal in its bog and muskeg habitats.^[3][5] Drought tolerance is rated medium, with native precipitation of 16–55 in (about 400–1,400 mm) per year.^[7] For groundcover use, plants are spaced about 25 cm apart, or roughly 700–1,700 plants per acre in revegetation mixes.^[6][7]

Sun and humidity

The plant grows in exposed, windy positions — open tundra, rockfields, coastal bluffs and peatland — where airflow is constant and atmospheric humidity is often high, and it accepts both full sun and partial shade in gardens.^[3][7][6] A Pacific Northwest grower reports healthy plants in both "super wet places" such as Crowberry Bog in Washington and dry, rocky patches in full sun, and describes the species as slow for the first few years before it "picks up speed."^[11]

Seasonal changes

Flowering begins in spring — May–June in European gardens — and continues into July at northern sites with early snowmelt; fruits mature from August to late fall and persist on the plant through winter under snow cover.^[3][6] In Lapland and other northern regions the berries are gathered in late winter from beneath the snow, and fruit that hangs on the plant into cold weather is generally regarded as better eating than early, unripe berries.^[3][6] The evergreen foliage carries the plant through winter; the species is hardy to very low temperatures (minimum about −43 °F/−42 °C in one propagation-compiled record).^[7]

Propagation

Seed is a slow route. The seeds have physiological dormancy and need cold moisture; the Baskin protocol calls for about 60 days of cold moist stratification, with germination at an alternating 20/15 °C cycle, while a stored-seed prescription gives 5 months of warm stratification followed by 3 months cold at 5 °C.^[7][6] In natural plantings, direct seeding does not work, seedlings are uncommon, and establishment can take decades; only a small percentage of seeds are viable.^[5][3] The main natural reproduction is vegetative: the plant sprouts from underground or basal portions and roots adventitiously wherever procumbent branches touch the ground.^[3]

Cuttings are the practical method. Leafy stem cuttings taken in mid-summer root easily in peat; half-ripe wood about 3 cm long with a heel, taken mid-summer, roots in about three weeks with a good percentage; mature wood of the current year's growth, 3 cm with a heel, roots in a cold frame in early autumn with shade.^[5][6] Plants do not regenerate from root cuttings or from prostrate leafless stems.^[5]

For mass production, in vitro micropropagation is the documented route — there are no industrial plantations of the species — followed by ex vitro rooting of microcuttings with mycorrhizal preparations.^[8] In a 2025 Russian rooting trial of the cultivar 'Irland', microcuttings rooted best on agroperlite treated with the mycorrhizal preparation 'Mycofriend', reaching 88.9% rooting with a mean of 4.0 roots and 6.24 cm total root length, versus 2.52 roots and 2.71 cm in the untreated control.^[13] In the companion container study, 0.5 L pots of high-moor peat (pH 4.0 or below) with effective fertilizer–mycorrhiza combinations raised total root length 30–50% and shoot length 40–80%, while a slow-release N19P9K10+2MgO fertilizer reduced survival to 29–75% and was judged detrimental.^[8]

Flowering, fruiting, and harvest

Pollination is the main cropping risk. The Alaska extension synthesis reports that wind pollination may be critical, that insects — particularly flies — are not ruled out, and that self-pollination is considered impossible or so slight that fruit yield is significantly reduced without cross-pollination.^[5] Grower experience points the same way: a Seattle-area grower with several Empetrum species reports that isolated plants in different parts of the yard "didn't produce anything," while plants placed close together set fruit, and he chose a synoecious hermaphroditum-type plant partly because it is described as self-fertile.^[11] Because accounts conflict — the extension literature regards even hermaphroditum-type plants as needing cross-pollination for full yield — the practical hedge is to plant several individuals rather than relying on a single plant.^[5][11]

Flowering runs spring through July depending on site; the inconspicuous pinkish flowers precede the fruit crop on the previous season's growth.^[3][5] Berries mature from August to late fall and stay on the plant through winter, which makes harvest timing flexible — picking can continue under snow cover in cold regions.^[3] Wild collection in Finland tolerates mechanical harvesting without hurting the crop: in a three-year field experiment at Rovaniemi, neither plastic hand rakes nor long-handled metal rakes (including a heavy rake pulled twice to the moss layer) reduced subsequent berry number or fresh weight of crowberry over two monitored years, and commercial rake-picking was comparable to hand-picking.^[9] Crowberry yields in the region are described as rather even between years; Finnish commercial purchases ran only 0–0.4 million kg per year during the study decade, against 3.1 million kg of bilberry in 2011.^[9]

Fruit and uses

The raw berry is small (4–10 mm), mealy and often tasteless or insipid on its own; after frost it is considered better, and most traditional use is cooked — jellies, pies, preserves and drinks — or as a mixer.^[5][6] In Lapland the berries serve as an extender and coloring agent in blueberry products; in North America they are gathered in winter from beneath the snow, and dried or frozen for later use.^[5][3][6] A purple dye can be made from the fruit.^[6]

The fruit is chemically notable: an analytical study identified 13 anthocyanins in freeze-dried crowberry powder by HPLC–MS, with cyanidin-3-galactoside (8.04 mg/g) and delphinidin-3-galactoside (8.62 mg/g) as the major pigments and a total anthocyanin content of 41.8 mg/g extract — higher than the nine other major berry species tested (2.5–38.8 mg/g), with the strongest antioxidant activity of the group in DPPH, ABTS and FRAP assays.^[10] These are laboratory measures of pigment and antioxidant capacity, not health-effect evidence. Extension sources also rate the berries very high in vitamin C and other antioxidants.^[5]

Traditional medicinal uses are recorded ethnobotanically — tea from the twigs, diuretic uses of leafy branches, decoctions of stems or cooked berries for diarrhoea, and a root decoction used as an eyewash — but these are traditional reports, not clinical evidence.^[6]

Cultivars and selections

Documented named material is thin, so the section is short by design.

'Irland' is a European variety used in clonal micropropagation research rather than a widely marketed garden cultivar. It is the cultivar in the 2025 microcuttings and container studies: in vitro establishment on Woody Plant Medium, ex vitro rooting improved by mycorrhizal preparations (88.9% rooting on agroperlite with 'Mycofriend'), and a strong response to fertilizer–mycorrhiza combinations in small peat containers, with slow-release high-phosphorus fertilizer clearly detrimental.^[8][13] It is a documented research line, not a release with grower trial data.

'Bernstein' is a nursery-listed selection of black crowberry with golden-yellow foliage that shifts to orange and bronze seasonally; a slow-growing undershrub reaching about 20 cm tall and 50 cm wide, it is sold as dioecious — a female plant needs at least one male nearby to fruit — with small pink flowers in May–June and black berries ripening in September.^[12] The listing claims sweet berries and hardiness to about −45.5 °C (zone 2), and recommends full sun to partial shade with non-chalky, moist acidic-to-neutral soil (pH 4.3–7); these remain commercial nursery claims — no formal cultivar registration or independent trial was located.^[12]

Photos

References

• ↑ [1] GBIF species match: Empetrum nigrum. Accepted backbone record (usageKey 8925249, exact match, confidence 99), family Ericaceae, genus Empetrum, order Ericales.

• ↑ [2] Plants of the World Online: Empetrum nigrum. Kew taxonomic backbone; accepted species, first published 1753, native subarctic to subalpine Northern Hemisphere, subshrub of the temperate biome.

• ↑ [3] Matthews 1992, Empetrum nigrum species review, USDA Forest Service FEIS (updated Aug 2025). Accepted name and synonymy with E. hermaphroditum; mat-forming habit, site pH 2.5–7.7, waterlogging intolerance, spring–July flowering, August–winter fruiting, seed viability, vegetative reproduction and layering, groundcover and fruit-use notes.

• ↑ [4] Empetrum nigrum, Flora of North America vol. 8 (Ericaceae). Treatment of E. nigrum in the broad sense; flower sexuality (synoecious, polygamous or dioecious), chromosome counts 2n = 26, 39, 52, drupe and seed measurements, subsumption of E. hermaphroditum tetraploids.

• ↑ [5] Holloway, Managing Wild Bog Blueberry, Lingonberry, Cloudberry and Crowberry Stands in Alaska, UAF Cooperative Extension/NRCS. Crowberry section: clump height to 10 in, rooting of procumbent stems, ssp. nigrum dioecy vs ssp. hermaphroditum, flower position and color, wind-pollination and self-incompatibility notes, seed stratification failure, cutting propagation, fruit size with 6–9 nutlets, raw flavor, Lapland uses, vitamin C.

• ↑ [6] Empetrum nigrum, Useful Temperate Plants. Calcifuge culture, sandy peaty soil, shade, dioecy in European forms, fruit size and flavor with frost improvement, winter persistence, Inuit storage, seed stratification schedules, cutting schedules, spacing, purple dye, traditional medicinal uses (ethnobotanical).

• ↑ [7] Turner 2012, Plant Propagation Protocol for Empetrum nigrum, University of Washington ESRM 412. Circumpolar distribution, habitat inventory, leaf morphology, pH min 4.3 max 7.8, drought tolerance, precipitation 16–55 in, minimum temperature −43 °F, 60-day cold moist stratification, germination cycle, planting density 700–1,700/acre, cutting notes, 6–9 nutlets and waxy coating.

• ↑ [8] Nechiporenko, Akimova & Semenova 2025, Mycorrhization of Black Crowberry After In Vitro Propagation with Mineral Fertilizers, Horticulturae 11(9):1063. Original container study of cv. 'Irland': soil pH 2.5–7.5 tolerance with death above 8.0 via ericoid mycorrhiza loss, no industrial plantations, in vitro multiplication, ex vitro adaptation, root/shoot response to fertilizer–mycorrhiza treatments, slow-release fertilizer detriment, 98-day juvenile window.

• ↑ [9] Manninen & Peltola 2013, Effects of picking methods on berry production of bilberry, lingonberry and crowberry in Northern Finland, Silva Fennica 47(3):972. Original field experiment: rake treatments did not reduce crowberry berry number or fresh weight over two monitored years; even yields; Finnish commercial purchase figures.

• ↑ [10] Ogawa et al. 2008, Anthocyanin composition and antioxidant activity of the Crowberry (Empetrum nigrum) and other berries, J. Agric. Food Chem. 56:4457–4462. Original analytical study (abstract): 13 anthocyanins, major cyanidin-3- and delphinidin-3-galactosides, total 41.8 mg/g extract vs 2.5–38.8 mg/g in nine other berries, strongest antioxidant activity in DPPH/ABTS/FRAP assays; abstract-limited access.

• ↑ [11] GrowingFruit.org thread 76104: Growing crowberries (Empetrum nigrum), Oct 2025. Attributed firsthand reports: Andy Barr (Seattle, WA area, posts 24–26 Oct 2025) — wet bog and dry rocky full-sun sites both work, slow early growth, easy cuttings, no fruit on isolated plants, improved set with close grouping, first-year yield too small for jam; 'TheNetherlands' chose a hermaphroditum-type plant described as self-fertile. Contextual anecdotal evidence, not generalized.

• ↑ [12] Empetrum nigrum 'Bernstein', Promesse de Fleurs nursery listing. Commercial listing: golden foliage selection, 20 × 50 cm habit, dioecious sex requirement, May–June flowers, September berries, pH 4.3–7, hardiness and flavor claims are nursery marketing, not independent trial data.

• ↑ [13] Nechiporenko et al. 2025, Features of rooting microcuttings of black crowberry (Empetrum nigrum L.) during adaptation, Vegetable Crops of Russia 2025(5):86–95. Original study (abstract): microcutting rooting of cv. 'Irland' on three substrates with five root-stimulant treatments; best rooting 88.9% on agroperlite with 'Mycofriend'; 4.0 roots and 6.24 cm root length vs control; 45-day mini-greenhouse phase; abstract-limited access.

Image credits

• Abuluntu Empetrum nigrum.jpg — berries of black crowberry, August 2021: Abuluntu, file page, CC BY-SA 4.0 (attribution and share-alike required).

• Black Crowberry (Empetrum nigrum) - Bay Roberts, Newfoundland 2019-08-12 (01).jpg — black crowberry plant in Bay Roberts, Newfoundland and Labrador, 12 August 2019: Ryan Hodnett, file page, CC BY-SA 4.0 (attribution and share-alike required).

• Black Crowberry (Empetrum nigrum) - Sandnes, Norway 2021-08-02.jpg — black crowberry plant in Sandnes, Norway, 2 August 2021: Ryan Hodnett, file page, CC BY-SA 4.0 (attribution and share-alike required).

• Blomstrende revling (Empetrum nigrum).jpeg — flowering black crowberry in Stråsø plantation near Ulfborg, Denmark, April 2020: Peterleth, file page, CC BY-SA 4.0 (attribution and share-alike required).

• 20121015-FS-UNK-0003 (8090983768).jpg — black crowberry with bunchberry (Cornus suecica) in an autumn muskeg near Sitka, Alaska, October 2012: U.S. Department of Agriculture (Mary Stensvold), file page, public domain (USDA). Caption names both species because the file description shows bunchberry alongside crowberry.